Preserving management services with distributed metadata through the disaster recovery life cycle

ABSTRACT

For disaster recovery involving a first site and a disaster recovery site, where at least a portion of management service metadata not isolated within the management service, a failover process is initiated, including creating an initial snapshot of the distributed metadata state. In a failback process, a representation is created of state changes for the management service and a delta description is calculated therefrom. The delta description is transmitted to the first site; and a reverse replica is created, at the first site, of all the workload components from the disaster recovery site. The delta description is played back to restore a distributed metadata state that existed in the disaster recovery site and to re-create it in the first site.

STATEMENT OF GOVERNMENT RIGHTS

Not Applicable.

CROSS-REFERENCE TO RELATED APPLICATIONS

Not Applicable.

FIELD OF THE INVENTION

The present invention relates to the electrical, electronic and computerarts, and, more particularly, to information technology and the like.

BACKGROUND OF THE INVENTION

Disaster recovery (DR) refers to the preparation for recovery orcontinuation of vital information technology infrastructure after adisaster. Current disaster recovery techniques primarily address statemaintenance of servers, and storage for servers and applications.

SUMMARY OF THE INVENTION

Principles of the invention provide techniques for preserving managementservices with distributed metadata through the disaster recovery lifecycle. In one aspect, an exemplary method includes the step of duringnormal operation, at a first site, of a disaster recovery managementunit including at least one customer workload machine and at least onemanagement service machine implementing at least one management service,replicating to a remote disaster recovery site the at least one customerworkload machine, the at least one management service machine, andmetadata for the at least one management service. At least a portion ofthe metadata is not isolated within the at least one management service.A further step includes, after a disaster at the first site, initiatinga failover process. The failover process in turn includes bringing up,at the remote disaster recovery site, a replicated version of the atleast one customer workload machine; Bringing up, at the remote disasterrecovery site, a replicated version of the at least one managementservice machine; operating, at the remote disaster recovery site, thereplicated version of the at least one customer workload machine and thereplicated version of the at least one management service machine, inaccordance with the metadata for the at least one management service;and creating an initial snapshot of a distributed metadata state of themetadata for the at least one management service implemented on thereplicated version of the at least one management service machine. Astill further step includes, subsequent to initiating the failoverprocess, initiating a failback process. The failback process includescreating a representation of state changes for the at least onemanagement service implemented on the replicated version of the at leastone management service machine made in the remote disaster recovery sitesince the failover process and calculating therefrom a delta descriptionfrom the initial snapshot; transmitting the delta description to thefirst site; and creating a reverse replica of all the workloadcomponents from the remote disaster recovery site at the first site andplaying back the delta description to restore a distributed metadatastate that existed in the remote disaster recovery site and re-create itin the first site.

As used herein, “facilitating” an action includes performing the action,making the action easier, helping to carry the action out, or causingthe action to be performed. Thus, by way of example and not limitation,instructions executing on one processor might facilitate an actioncarried out by instructions executing on a remote processor, by sendingappropriate data or commands to cause or aid the action to be performed.For the avoidance of doubt, where an actor facilitates an action byother than performing the action, the action is nevertheless performedby some entity or combination of entities.

One or more embodiments of the invention or elements thereof can beimplemented in the form of a computer program product including acomputer readable storage medium with computer usable program code forperforming the method steps indicated. Furthermore, one or moreembodiments of the invention or elements thereof can be implemented inthe form of a system (or apparatus) including a memory, and at least oneprocessor that is coupled to the memory and operative to performexemplary method steps. Yet further, in another aspect, one or moreembodiments of the invention or elements thereof can be implemented inthe form of means for carrying out one or more of the method stepsdescribed herein; the means can include (i) hardware module(s), (ii)software module(s) stored in a computer readable storage medium (ormultiple such media) and implemented on a hardware processor, or (iii) acombination of (i) and (ii); any of (i)-(iii) implement the specifictechniques set forth herein.

Techniques of the present invention can provide substantial beneficialtechnical effects. One example of a managed service with distributedmetadata that can continue to be supported after a disaster, and alsoafter recovery, is virtual resource provisioning in a Cloud. Suchsupport will allow normal operations in a Cloud to continue seamlesslyafter a disaster rather than constrained operations (with noprovisioning allowed), which is typical of how systems are run after adisaster, with the expectation that normal operations will be resumedsoon.

These and other features and advantages of the present invention willbecome apparent from the following detailed description of illustrativeembodiments thereof, which is to be read in connection with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts a cloud computing node according to an embodiment of thepresent invention;

FIG. 2 depicts a cloud computing environment according to an embodimentof the present invention;

FIG. 3 depicts abstraction model layers according to an embodiment ofthe present invention;

FIG. 4 depicts failover in a disaster recovery system with a monitoringscenario and asynchronous storage replication, useful withself-contained metadata;

FIG. 5 depicts failback in a disaster recovery system with a monitoringscenario and asynchronous storage replication, useful withself-contained metadata;

FIG. 6 is a flow chart of disaster recovery failover for monitoring,useful with self-contained metadata;

FIG. 7 is a detailed flow chart of one possible manner of carrying outstep 608 in FIG. 6, useful with self-contained metadata;

FIG. 8 is a detailed flow chart of one possible manner of carrying outstep 610 in FIG. 6, useful with self-contained metadata;

FIG. 9 depicts synchronous file level replication, useful withself-contained metadata; and

FIG. 10 shows exemplary meta-data for a monitoring example, useful withself-contained metadata;

FIG. 11 depicts an exemplary disaster recovery and provisioning scenariowith storage replication, in a failback mode, useful with distributedmetadata, in accordance with an aspect of the invention;

FIG. 12 depicts preservation of virtual machine provisioning management,useful with distributed metadata, in accordance with an aspect of theinvention; and

FIG. 13 presents a table of delta descriptions and execution steps in aprimary site failback manager upon failback, in accordance with anaspect of the invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

It is understood in advance that although this disclosure includes adetailed description on cloud computing, implementation of the teachingsrecited herein are not limited to a cloud computing environment. Rather,embodiments of the present invention are capable of being implemented inconjunction with any other type of computing environment now known orlater developed.

Cloud computing is a model of service delivery for enabling convenient,on-demand network access to a shared pool of configurable computingresources (e.g. networks, network bandwidth, servers, processing,memory, storage, applications, virtual machines, and services) that canbe rapidly provisioned and released with minimal management effort orinteraction with a provider of the service. This cloud model may includeat least five characteristics, at least three service models, and atleast four deployment models.

Characteristics are as follows:

On-demand self-service: a cloud consumer can unilaterally provisioncomputing capabilities, such as server time and network storage, asneeded automatically without requiring human interaction with theservice's provider.

Broad network access: capabilities are available over a network andaccessed through standard mechanisms that promote use by heterogeneousthin or thick client platforms (e.g., mobile phones, laptops, and PDAs).

Resource pooling: the provider's computing resources are pooled to servemultiple consumers using a multi-tenant model, with different physicaland virtual resources dynamically assigned and reassigned according todemand. There is a sense of location independence in that the consumergenerally has no control or knowledge over the exact location of theprovided resources but may be able to specify location at a higher levelof abstraction (e.g., country, state, or datacenter).

Rapid elasticity: capabilities can be rapidly and elasticallyprovisioned, in some cases automatically, to quickly scale out andrapidly released to quickly scale in. To the consumer, the capabilitiesavailable for provisioning often appear to be unlimited and can bepurchased in any quantity at any time.

Measured service: cloud systems automatically control and optimizeresource use by leveraging a metering capability at some level ofabstraction appropriate to the type of service (e.g., storage,processing, bandwidth, and active user accounts). Resource usage can bemonitored, controlled, and reported providing transparency for both theprovider and consumer of the utilized service.

Service Models are as follows:

Software as a Service (SaaS): the capability provided to the consumer isto use the provider's applications running on a cloud infrastructure.The applications are accessible from various client devices through athin client interface such as a web browser (e.g., web-based email). Theconsumer does not manage or control the underlying cloud infrastructureincluding network, servers, operating systems, storage, or evenindividual application capabilities, with the possible exception oflimited user-specific application configuration settings.

Platform as a Service (PaaS): the capability provided to the consumer isto deploy onto the cloud infrastructure consumer-created or acquiredapplications created using programming languages and tools supported bythe provider. The consumer does not manage or control the underlyingcloud infrastructure including networks, servers, operating systems, orstorage, but has control over the deployed applications and possiblyapplication hosting environment configurations.

Infrastructure as a Service (IaaS): the capability provided to theconsumer is to provision processing, storage, networks, and otherfundamental computing resources where the consumer is able to deploy andrun arbitrary software, which can include operating systems andapplications. The consumer does not manage or control the underlyingcloud infrastructure but has control over operating systems, storage,deployed applications, and possibly limited control of select networkingcomponents (e.g., host firewalls).

Deployment Models are as follows:

Private cloud: the cloud infrastructure is operated solely for anorganization. It may be managed by the organization or a third party andmay exist on-premises or off-premises.

Community cloud: the cloud infrastructure is shared by severalorganizations and supports a specific community that has shared concerns(e.g., mission, security requirements, policy, and complianceconsiderations). It may be managed by the organizations or a third partyand may exist on-premises or off-premises.

Public cloud: the cloud infrastructure is made available to the generalpublic or a large industry group and is owned by an organization sellingcloud services.

Hybrid cloud: the cloud infrastructure is a composition of two or moreclouds (private, community, or public) that remain unique entities butare bound together by standardized or proprietary technology thatenables data and application portability (e.g., cloud bursting for loadbalancing between clouds).

A cloud computing environment is service oriented with a focus onstatelessness, low coupling, modularity, and semantic interoperability.At the heart of cloud computing is an infrastructure comprising anetwork of interconnected nodes.

Referring now to FIG. 1, a schematic of an example of a cloud computingnode is shown. Cloud computing node 10 is only one example of a suitablecloud computing node and is not intended to suggest any limitation as tothe scope of use or functionality of embodiments of the inventiondescribed herein. Regardless, cloud computing node 10 is capable ofbeing implemented and/or performing any of the functionality set forthhereinabove.

In cloud computing node 10 there is a computer system/server 12, whichis operational with numerous other general purpose or special purposecomputing system environments or configurations. Examples of well-knowncomputing systems, environments, and/or configurations that may besuitable for use with computer system/server 12 include, but are notlimited to, personal computer systems, server computer systems, thinclients, thick clients, handheld or laptop devices, multiprocessorsystems, microprocessor-based systems, set top boxes, programmableconsumer electronics, network PCs, minicomputer systems, mainframecomputer systems, and distributed cloud computing environments thatinclude any of the above systems or devices, and the like.

Computer system/server 12 may be described in the general context ofcomputer system executable instructions, such as program modules, beingexecuted by a computer system. Generally, program modules may includeroutines, programs, objects, components, logic, data structures, and soon that perform particular tasks or implement particular abstract datatypes. Computer system/server 12 may be practiced in distributed cloudcomputing environments where tasks are performed by remote processingdevices that are linked through a communications network. In adistributed cloud computing environment, program modules may be locatedin both local and remote computer system storage media including memorystorage devices.

As shown in FIG. 1, computer system/server 12 in cloud computing node 10is shown in the form of a general-purpose computing device. Thecomponents of computer system/server 12 may include, but are not limitedto, one or more processors or processing units 16, a system memory 28,and a bus 18 that couples various system components including systemmemory 28 to processor 16.

Bus 18 represents one or more of any of several types of bus structures,including a memory bus or memory controller, a peripheral bus, anaccelerated graphics port, and a processor or local bus using any of avariety of bus architectures. By way of example, and not limitation,such architectures include Industry Standard Architecture (ISA) bus,Micro Channel Architecture (MCA) bus, Enhanced ISA (EISA) bus, VideoElectronics Standards Association (VESA) local bus, and PeripheralComponent Interconnect (PCI) bus.

Computer system/server 12 typically includes a variety of computersystem readable media. Such media may be any available media that isaccessible by computer system/server 12, and it includes both volatileand non-volatile media, removable and non-removable media.

System memory 28 can include computer system readable media in the formof volatile memory, such as random access memory (RAM) 30 and/or cachememory 32. Computer system/server 12 may further include otherremovable/non-removable, volatile/non-volatile computer system storagemedia. By way of example only, storage system 34 can be provided forreading from and writing to a non-removable, non-volatile magnetic media(not shown and typically called a “hard drive”). Although not shown, amagnetic disk drive for reading from and writing to a removable,non-volatile magnetic disk (e.g., a “floppy disk”), and an optical diskdrive for reading from or writing to a removable, non-volatile opticaldisk such as a CD-ROM, DVD-ROM or other optical media can be provided.In such instances, each can be connected to bus 18 by one or more datamedia interfaces. As will be further depicted and described below,memory 28 may include at least one program product having a set (e.g.,at least one) of program modules that are configured to carry out thefunctions of embodiments of the invention.

Program/utility 40, having a set (at least one) of program modules 42,may be stored in memory 28 by way of example, and not limitation, aswell as an operating system, one or more application programs, otherprogram modules, and program data. Each of the operating system, one ormore application programs, other program modules, and program data orsome combination thereof, may include an implementation of a networkingenvironment. Program modules 42 generally carry out the functions and/ormethodologies of embodiments of the invention as described herein.

Computer system/server 12 may also communicate with one or more externaldevices 14 such as a keyboard, a pointing device, a display 24, etc.;one or more devices that enable a user to interact with computersystem/server 12; and/or any devices (e.g., network card, modem, etc.)that enable computer system/server 12 to communicate with one or moreother computing devices. Such communication can occur via Input/Output(I/O) interfaces 22. Still yet, computer system/server 12 cancommunicate with one or more networks such as a local area network(LAN), a general wide area network (WAN), and/or a public network (e.g.,the Internet) via network adapter 20. As depicted, network adapter 20communicates with the other components of computer system/server 12 viabus 18. It should be understood that although not shown, other hardwareand/or software components could be used in conjunction with computersystem/server 12. Examples, include, but are not limited to: microcode,device drivers, redundant processing units, and external disk drivearrays, RAID systems, tape drives, and data archival storage systems,etc.

Referring now to FIG. 2, illustrative cloud computing environment 50 isdepicted. As shown, cloud computing environment 50 comprises one or morecloud computing nodes 10 with which local computing devices used bycloud consumers, such as, for example, personal digital assistant (PDA)or cellular telephone 54A, desktop computer 54B, laptop computer 54C,and/or automobile computer system 54N may communicate. Nodes 10 maycommunicate with one another. They may be grouped (not shown) physicallyor virtually, in one or more networks, such as Private, Community,Public, or Hybrid clouds as described hereinabove, or a combinationthereof. This allows cloud computing environment 50 to offerinfrastructure, platforms and/or software as services for which a cloudconsumer does not need to maintain resources on a local computingdevice. It is understood that the types of computing devices 54A-N shownin FIG. 2 are intended to be illustrative only and that computing nodes10 and cloud computing environment 50 can communicate with any type ofcomputerized device over any type of network and/or network addressableconnection (e.g., using a web browser).

Referring now to FIG. 3, a set of functional abstraction layers providedby cloud computing environment 50 (FIG. 2) is shown. It should beunderstood in advance that the components, layers, and functions shownin FIG. 3 are intended to be illustrative only and embodiments of theinvention are not limited thereto. As depicted, the following layers andcorresponding functions are provided:

Hardware and software layer 60 includes hardware and softwarecomponents. Examples of hardware components include mainframes, in oneexample IBM® zSeries® systems; RISC (Reduced Instruction Set Computer)architecture based servers, in one example IBM pSeries® systems; IBMxSeries® systems; IBM BladeCenter® systems; storage devices; networksand networking components. Examples of software components includenetwork application server software, in one example IBM WebSphere®application server software; and database software, in one example IBMDB2® database software. (IBM, zSeries, pSeries, xSeries, BladeCenter,WebSphere, and DB2 are trademarks of International Business MachinesCorporation registered in many jurisdictions worldwide).

Virtualization layer 62 provides an abstraction layer from which thefollowing examples of virtual entities may be provided: virtual servers;virtual storage; virtual networks, including virtual private networks;virtual applications and operating systems; and virtual clients.

In one example, management layer 64 may provide the functions describedbelow. Resource provisioning provides dynamic procurement of computingresources and other resources that are utilized to perform tasks withinthe cloud computing environment. Metering and Pricing provide costtracking as resources are utilized within the cloud computingenvironment, and billing or invoicing for consumption of theseresources. In one example, these resources may comprise applicationsoftware licenses. Security provides identity verification for cloudconsumers and tasks, as well as protection for data and other resources.User portal provides access to the cloud computing environment forconsumers and system administrators. Service level management providescloud computing resource allocation and management such that requiredservice levels are met. Service Level Agreement (SLA) planning andfulfillment provides pre-arrangement for, and procurement of, cloudcomputing resources for which a future requirement is anticipated inaccordance with an SLA.

Workloads layer 66 provides examples of functionality for which thecloud computing environment may be utilized. Examples of workloads andfunctions which may be provided from this layer include: mapping andnavigation; software development and lifecycle management; virtualclassroom education delivery; data analytics processing; transactionprocessing; and mobile desktop.

As noted, disaster recovery (DR) refers to the preparation for recoveryor continuation of vital information technology infrastructure andapplications after a disaster. Current disaster recovery techniquesprimarily address state maintenance of servers and storage for serversand applications.

Advantageously, one or more embodiments provide an approach to preservemonitoring and event management services for failed-over systems in therecovery site after a disaster. One or more embodiments apply to managedservices whose meta-data that is impacted by the DR failover/failbackprocess is distributed. However, to facilitate the disclosure of one ormore embodiments, a description will first be provided of embodimentsthat apply to managed services whose meta-data that is impacted by theDR failover/failback process is contained within the managed serviceitself (self-contained).

One or more embodiments are generally applicable to management serviceswith distributed metadata. A non-limiting example is provided in thecontext of Virtual Machine provisioning (of a management service withdistributed metadata)—which is a Cloud Computing example. However, oneor more embodiments can also be applied to Physical Machine provisioningalso in a data center. Furthermore, another non-limiting example ofmanagement services with distributed metadata is so-called HighAvailability (HA), where the approach outlined in this application canalso be applied with suitable customizations.

Self-contained Metadata

In some cases, each management service maintains meta-data includingthat required for multi-tenancy support. This meta-data, in someembodiments, has to be replicated with a higher recovery point objective(RPO) (no-loss), and, after the DR, the meta-data has to be fixed upbased on the state of the recovered virtual machines (VMs).

One or more embodiments are applicable to disaster recovery in bothcloud environments and traditional (non-virtualized) data centers,including those with multi-tenancy such as hosting services.

Thus, when managed services are employed in an IT environment, themanagement layer 64 needs to be failed over to the disaster recoverysite in the event of an outage. Monitoring is one non-limiting exampleof a management layer function. Typically, each of the managed servicesmaintains some metadata, such as endpoints, customer virtual machines(VMs), and so on. In the case of event management, the metadata will bethe policies that specify what is to be done upon the occurrence ofcertain events. In one or more embodiments, this metadata is failed overand fixed up (also referred to herein as “reconfigured”) in therecovered VM(s) in the disaster recovery site.

As noted, current disaster recovery techniques primarily cover statemaintenance of servers and applications such as storage for servers andapplications. From a cloud perspective, these servers and applicationsare typically managed entities. Advantageously, one or more embodimentsextend DR to the state maintenance of the managing entities. Someembodiments reuse some existing techniques such as storage replicationthat are used for the managed entities; however, these existingtechniques are modified in one or more embodiments to provide additionalpre-failover configuration and post-failover processing.

Again, it is to be emphasized that monitoring and/or event managementare non-limiting exemplary applications; patching, identity management,asset management, and discovery processing are other non-limitingexamples. In a cloud environment, as noted, there is a management layer64 where there are tools running to manage the cloud: monitoring,patching, identity management, asset management, and so on. When adisaster occurs, there is a transition from the site where the disasterhas occurred to the disaster recovery site; as part of this process,management layer 64 is failed over to the disaster recovery (failover)site. Failover of VMs, file structures, and the like are known fromprior art. As noted, each of the management services typically maintainssome metadata. Again, in the example of monitoring, metadata includesVMs, infrastructure layer, and the tools in the management stack; in theexample of event management, metadata includes policies setting forthwhat needs to be done when an event comes in for a specific customer. Anexample of this includes automation policies per customer—certainautomated remediation actions are taken if something happens on thecustomer's VM; e.g., a file system problem. Another example of meta-dataincludes the severity, threshold, sampling interval, and persistencethat should be used to raise an alert for a customer VM. Another exampleof meta-data includes automation policies per customer that shoulddetermine how and where the event should be ticketed and routed.

Typically, data must be failed over and fixed up in the recovered VM inthe failover site.

It is important to note that one or more embodiments are directed tofailover for the items that manage the customer's workload as opposed tothe customer's workload per se.

Attention should now be given to FIG. 4, which depicts failover in adisaster recovery system with a monitoring scenario and asynchronousstorage replication. Note two sites 402, 404 where customer workloadsare running—these can be cloud or non-cloud sites, and there can be anynumber of sites, as indicated by the ellipsis. Replicas reside atdisaster recovery (DR) site 406.

More particularly, first site 402, also designated as Site_1, includesCustomer Server_1, designated as 414, Monitoring Server_1, designated as416, and Policy Mapper_1, designated as 408, all coupled to StorageSystem_1, designated as 434. Furthermore, n^(th) site 404, alsodesignated as Site_n, includes Customer Server_n, designated as 418,Monitoring Server n, designated as 420, and Event-Policy Mapper_n,designated as 422, all coupled to Storage System_n, designated as 436.Disaster recovery (DR) site 406 includes Customer Server_1 replica,designated as 438, Monitoring Server_1 replica, designated as 422, andPolicy Mapper_1, designated as 426, all coupled to the DR storagesystem, designated as 412. Furthermore, DR site 406 further includesCustomer Server_n replica, designated as 428, Monitoring Server_nreplica, designated as 430, and Event-Policy Mapper_n replica,designated as 432, also all coupled to the DR storage system 412.Finally, DR site 406 includes DR failover manager 410 which orchestratesthe failover process; the failover process includes not onlyconventional failover of the workloads but also of the monitoringservers 416, 420 and the policy mappers 408, 422.

Note that in general, a “PoD” (point of deployment) is a unit ofmanagement, and a site 402, 404 can, in general, include one or morePoDs. In order to be a management unit for disaster recovery purposes,there should be a centralized repository of MS (monitoring server)instances and topology. One or more embodiments employ per-MSconfiguration fix-up scripts for failover and failback, and make use ofMS APIs (application program interfaces).

In FIG. 4, the asynchronous storage system replication is indicated bythe bold curved arrows from the storage systems 434, 436 to the DRstorage system 412. Software based replication also applies to one ormore embodiments.

In normal operation, the customer servers 414, 418 (which, in general,can be real or virtual, although of course even virtual serversultimately reside on one or more real machines) run one or more customerworkloads. The monitoring servers 416, 420 monitor those workloads anddetect events. The policy mappers 408, 422 work closely with themonitoring servers 416, 420 to initiate action in response to the eventsdetected by the servers 416, 420 according to the corresponding mappingbetween events and policies. Each of the servers and mappers in thesites 402, 404 is asynchronously (not real time) replicated in the DRsite 406.

When a disaster occurs (e.g., power outage), the workload and at least asubset of the servers are brought up at DR site 406. The customerservers can be brought up one-by-one by using the replicated volume.However, while, say, a server is now “up” to handle the workload, it isnot being monitored; alerts are not being generated. In one or moreembodiments, to address bringing up the managed service(s), monitoringservers and policy mappers have also been replicated, as seen at 424,426, 430, 432 and eventually are brought up as well. However, endpointaddresses have changed—therefore, the replicas can't immediately monitorthe replicated servers in the DR site 406; a fix-up is needed so thatthey can monitor the replicated servers in the DR environment. One ormore embodiments employ metadata to facilitate the fix-up process.

FIG. 5 depicts failback in the disaster recovery system with monitoringscenario and asynchronous storage replication of FIG. 4. When the mainsite (here, Site_n 404) comes back up, begin background replication asindicated by the bold arrows from DR storage system 412 to storagesystems 434, 436. For the avoidance of doubt, FIG. 5 depicts a conditionwherein only Site_n is shown as being down. When this replication iscomplete, the reverse of the process described with regard to FIG. 4 iscarried out, including for the monitoring servers and event policymappers. Using site-level failback manager 597 and DR failback manager599, start the machines at site 404, and eventually shut off themachines in DR site 406. Again, endpoint addresses have changed back tooriginal—therefore, the reconstituted servers 420, 422 can't immediatelymonitor the reconstituted server 418 in the site 404; a fix-up is neededso that they can monitor the reconstituted server(s) in the site 404.One or more embodiments employ metadata to facilitate this fix-upprocess, as well.

It will be appreciated that at least some managed services run (as oneor more VMs) independently of customer VMs, and that metadata and/orstate is local to the managed service. In one or more embodiments,operations to enable failover after PoD failure and failback once thePoD is again operational are as follows:

-   -   Steady state: Continuous (optionally asynchronous) replication        of state of PoD-MS 420 to DR site    -   Failover: Extraction of state from MS replica 430, and        subset+merge with DR-MS instance 430    -   Failback: Optionally merge the state of DR-MS instance 430 with        PoD-MS state 420 in replica of site 404

As noted, one or more embodiments use metadata to facilitate managementservices after disaster recovery. One simple example is in the case of afirewall. The metadata includes the rules in the firewall policy file.These rules become invalid when the firewall is moved to the DR site406, because there are new IP addresses. A simple map of the IPaddresses associated with site 404 to those associated with DR site 406can be used for the fix-up.

The metadata is more complex where the failed-over managed service is amonitoring service. Typically, the metadata in such a case is internallyrepresented in non-relational databases. One or more embodimentsleverage application program interface(s) (API(s)) provided by themonitoring services. An agent is installed on the VM to be monitored,together with appropriate rules. When provisioning the VM, it is set upfor monitoring. It is worth noting that IBM TIVOLI MONITORING softwareavailable form International Business Machines Corporation, Armonk,N.Y., USA, is one non-limiting example of software that could be run onservers 416, 420, 912, 424, 430, 914 (FIG. 9 is discussed elsewhereherein). This TIVOLI software has commands that can be used to set a VMup for monitoring. Note that elements 414, 418, 438, 428 are customervirtual machines but they do not necessarily have to be virtual; theycould be physical in some circumstances. FIG. 6 is a flow chart ofdisaster recovery failover for monitoring. In step 602, failover to theDR site 406 is triggered. In step 604, start VMs in DR site 406 based onpriorities from replica disk images (e.g., “Platinum,” “Gold,”“Silver”). In step 606, reconfigure the VM host names and IP addressesand start the VMs in DR site 406. Steps 602, 604, and 606 are analogousto those known from the prior art. In step 608, run a failover script onmonitoring server 420 and customer VM (with agents) to set themonitoring server replica 430 up to run on DR site 406 after failover.FIG. 6 shows the steps in a typical chronological order. Non-limitingexemplary details of step 608 are given in FIG. 7. In step 610, run afailover script on Event-Policy Mapper server 422 to set theEvent-Policy Mapper server replica 432 up to run on DR site 406 afterfailover. Non-limiting exemplary details of step 610 are given in FIG.8. Processing ends at 612.

Furthermore in this regard, in one or more embodiments, each of theservers 416, 408, 420, 422, 424, 426, 430, and 432 is provided with afailover script and a failback script. The scripts can be written, forexample, in Perl, Java, or any other suitable current programminglanguage. Furthermore, each VM (or physical machine) monitored by eachmonitoring server is provided with an agent. Refer to servers 414, 418,438, 428. The agents are registered on machines 416, 420, 424, 430respectively. Additionally, the agents installed on machines 414, 418,438, 428 report the collected metrics to the monitoring servers 416,420, 424, 430, respectively. Steps 608, 610 are repeated for eachmanaged service.

FIG. 7 is a detailed flow chart of one possible manner of carrying outstep 608 in FIG. 6. In a non-limiting exemplary embodiment, at 702, runa monitoring configuration fix-up script on server 430. The scripttypically has certain common script characteristics; for example, thescript contains a mapping of old identities (host name and/or IP addressin site 404) to new IDs in DR site 406; the script has root access toall VMs to perform fix-up; and this is arranged for by DR failovermanager 410, which needs similar access. At 704, the script runsmonitoring server commands (e.g., command line interface (CLI) or API)to “dump” configuration state and save it locally in 424 (e.g., whatcustomer VMs have which monitoring agents installed and/or what rulesare deployed to the agent for automated alerts). At 706, the scriptconnects to each customer VM 428 with monitoring installed, anduninstalls existing agents and rules. In step 708, the script usesmonitoring server commands to then reconfigure the entire monitoring onall customer VMs using new identities (host name and/or IP address);i.e., to reinstall agent(s) and redeploy rules. This can optionally bedone in a batch process. In step 710, update the monitoring serverconfiguration file to change reference to the Event-Policy Mapper 422based on its new identity 432. In one or more embodiments, appropriatescripts and/or agents run in site 406 after a disaster has occurred).

FIG. 8 is a detailed flow chart of one possible manner of carrying outstep 610 in FIG. 6. In step 802, run an event-policy mapperconfiguration fix-up (failover) script on server 432. Servers 408, 422typically have limited metadata, but do have a list (database or DB) ofevents wherein the sources (e.g., VMs) are identified by the oldaddresses in site 404. In one or more embodiments, common scriptassumption apply; for example, assume no “wiring” of the Event-PolicyMapper to any other MS instance (e.g., ticketing). In step 804, theevent DB entries contain old identities of event sources (e.g., VMs).The simplest “fix-up” approach is typically to remove all event entrieswith such old identities. A more complex “fix-up” approach is to updateeach event DB entry to replace the old identity (host name and/or IPaddress) with the new identity.

Consider the case of failback for monitoring, referring again to FIG. 5.Heretofore, in current systems, for each customer VM, the logical units(LUs) of the VM disks are replicated from the DR site to the “n^(th)”PoD “PoD_n.” Once synch-up is nearly complete, the managed VM is takento a quiescent state, final synch-up is completed, and the customer VMin PoD_n is started. In some instances, this latter step might have tobe delayed.

In one or more embodiments of the invention, which utilize a monitoringserver and policy mapper, delay the step of starting the customer VM 418in PoD_n 404 for managed VMs. For the monitoring server VM, reversemerge the config (configuration file) of the DR site's monitoring server430 to the PoD_n monitoring server config replica 420. Reverse merge ofconfigurations into the monitoring server is typically only done for thecustomer system groups corresponding to PoD_n managed VMs. During theconfiguration merge, it may be the case that new rules were definedand/or some rules were deleted or modified in the DR site 406. Theoriginal IP address for each record is still valid; no change isrequired. Replicate the LU of the PoD_n monitoring server to PoD_n. Inone or more embodiments, IP address fix-ups are not required because themonitoring server has the old IP address that is valid in the primarysite 404.

The steps just described are repeated for the policy mapper VM 432 beingfailed back to the replicated machine 422.

The customer VMs are started in PoD_n 404. Management of these VMs isthen commenced. Note that reversing the starting and managing for theseVMs could potentially lead to complexity in managing systems. Forexample, the new rules that were added while PoD n in 406 will not beevaluated, deleted rules that were removed while in PoD_n in 406 willcontinue to be evaluated or rules that were modified in PoD_n in 406will evaluate incorrectly.

FIG. 9 depicts synchronous file level replication. In one or moreembodiments, storage system volumes are dedicated to VMs. However,VMware VMFS is a counter-example to this case. VMware VMFS (VirtualMachine File System) is a cluster file system available from VMware,Inc. of Palo Alto, Calif., USA. Other embodiments can be adopted for usewith VMware VMFS and similar systems. For example, mount the VMFS filein loopback mount mode. With asynchronous replication, the contents ofthe master (Monitoring Server_1 912 in PoD_1 902) are not up to datewith the DR replica (Monitoring Server_1 replica 914 in DR site 908), asindicated by the notation “whole volume not replicated.” The lagdetermines RPO. If the monitoring and/or policy server configuration isupdated, DR site 908 will not “see” this for some predetermined timeperiod; say, “X” seconds. If a PoD disaster occurs between configurationupdate and replica update, the DR site will not restart with the latestPoD configuration. One possible approach is to employ limitedsynchronous replication 906.

The skilled artisan will appreciate that different management serviceswill have different types of metadata. In the case of monitoring andevent management, monitoring metadata typically includes rules todetermine when metrics from an entity indicate incidents (events), whileevent management metadata includes customer specific policies regardingautomated ticket handling (ticketing system, support group, severity,etc.) in response to incidents (events). In the case of patchmanagement, metadata includes the entity to be patched, current patchlevel, patch priority and schedule, and the like. In the case offirewalls, metadata includes allowing/disallowing inbound/outboundtraffic to/from specific networking endpoints (IP addresses and ports).

FIG. 10 shows non-limiting exemplary meta-data; in particular,monitoring meta-data 1002, first event management meta-data 1004; andsecond event management meta-data 1006. Post-disaster recovery fix-up ofmonitoring meta-data is shown at 1008. Post-disaster recovery fix-up ofevent management meta-data 1004 is shown at 1010.

The skilled artisan will appreciate that many other cases can be handledby the self-contained meta-data approach in addition to the non-limitingexemplary embodiment. For example, consider a virtual load balancingfirewall running in a fully-managed, highly secure IaaS cloud such asIBM Cloud Managed Services (formerly known as IBM SMART CLOUD ENTERPRISEPLUS) available from International Business Machines Corporation,Armonk, N.Y., USA. Consider such a load balancing firewall running on aVM, one per customer. In a non-limiting exemplary embodiment, each entryis of the following form:

-   -   Key=Source IP address/subnet, Dest. IP addr./subnet, destination        port, protocol    -   Value=allow/disallow (access)

After DR, typically, only a subset of the entries will be relevant andthe destination as well as the source internet protocol (IP) addresseswill need fix-up. For example, the managing systems could be the source.

Distributed Metadata

One or more embodiments provide techniques to preserve managementservices with distributed metadata through the disaster recovery lifecycle. One or more embodiments extend the techniques described above forself-contained metadata, to address management services with morecomplex metadata. In one or more embodiments, the metadata is notisolated within the management service. For example, parts of themetadata required for operation of the service may be stored in theinfrastructure layer, to which the management service has no access. Or,the failover site where customer applications run after a disaster mayuse an alternate instance of the management service, which has to beceded control. One or more embodiments are able to handle thatconstraint for management service preservation (e.g., virtual machine(VM) provisioning service). Furthermore, parts of the metadata may bestored in customer virtual servers; this extends the scope andcomplexity of the process of management service preservation.Non-limiting examples include High Availability service, e.g., TivoliSystems Automation (TSA), High Availability Clustered Management Program(HACMP), Microsoft Cluster Services (MSCS), and the like.

One or more embodiments are, as noted above, applicable to physicaland/or virtual machines, and to cloud and/or non-cloud environments.

Heretofore, disaster recovery (DR) has primarily covered statemaintenance of servers and applications such as storage for servers andapplications. From the cloud perspective, these servers and applicationsare managed entities. One or more embodiments extend DR to the statemaintenance of the managing entities, even where the metadata is notisolated within the management service.

Consider “Normal,” provisioning, and high availability (HA) managedservice metadata preservation. Many managed services run, as one or moreVMs, independently of customer VMs, and can be handled by the“self-contained” embodiments set forth above. Metadata and state arelocal to the managed service. Operations to enable failover after PoDfailure and failback once PoD is operational include:

-   -   1. Steady state: Continuous (possibly asynchronous) replication        of PoD-MS state to DR site    -   2. Failover: Extraction of state from MS replica, and        subset+merge with DR-MS instance    -   3. Failback: Optional merge of DR-MS instance state with PoD-MS        state in replica    -   4. Failback: Optional replication of DR-site replica to PoD if        PoD-MS state updated in item 3.

One or more embodiments herein are directed to cases with distributedmetadata. Consider, for example, a provisioning service. Provisioningraises an interesting complication: if provisioning is allowed in the DRsite after failover, then provisioning actions have to be repeated inthe primary site after failback. Placement decisions (e.g., whichhypervisor to run a VM on) made by the DR site PS (provisioning service)1129 in FIG. 11 will not make sense in the primary site. In the failoversite, metadata about how a VM and its dependent resources are allocatedis distributed across the DR site PS, and inside hypervisors, networkswitches/bridges and storage systems. Furthermore, resource constraintsin the DR site are not identical to the primary site.

Consider the non-limiting example of HA Clusters. For applicationclusters created with TSA-like tools, part of the metadata is in thecustomer VMs, since global cluster state is maintained by sharing localstate across cluster nodes using distributed systems protocols resilientto node and network failures.

Attention should now be given to FIG. 11, which depicts an exemplarydisaster recovery and provisioning scenario with storage replication, ina failback mode, useful with distributed metadata, in accordance with anaspect of the invention. Note two sites 1102, 1104 where customerworkloads have been running—these can be cloud or non-cloud sites, andthere can be any number of sites, as indicated by the ellipsis. Replicasof server storage units (disk drives or volumes) made during normaloperation, prior to failure, reside at disaster recovery (DR) site 1106.

More particularly, first site 1102, also designated as Site_1, includesCustomer Server_1, designated as 1114 and Provisioning Service_1,designated as 1116, and coupled to Storage System1, designated as 1134.Also included is a site-level disaster recovery manager 1192-1 includinga site-level failover manager 1194-1 and a site-level failback manager1197-1. Furthermore, n^(th) site 1104, also designated as Site_n,includes Customer Server_n, designated as 1118, and ProvisioningService_n, designated as 1120, and coupled to Storage System_n,designated as 1136. Also included is a site-level disaster recoverymanager 1192-2 including a site-level failover manager 1194-2 and asite-level failback manager 1197-2. The provisioning services create newVMs, modify VM properties, add memory, and so on.

Disaster recovery (DR) site 1106 includes Customer Server_1 replica,designated as 1138, and Primary site Provisioning Service_1 replicadesignated as 1124, all coupled to the DR storage system, designated as1112. Furthermore, DR site 1106 further includes Customer Server_nreplica, designated as 1128, DR site provisioning service 1129, andPrimary (abbreviated herein as “Pry”) site Provisioning Service_nreplica, designated as 1130, also all coupled to the DR storage system1112. Finally, DR site 1106 includes disaster recovery manager 1185including failover manager 1187 and DR Failback manager 1199 whichorchestrates the failback process. Elements 1129, 1130 may or may not bethe same.

Consider now provisioning preservation after failover and failback. Inparticular, consider preservation of VM provisioning management afterfailover and failback. One significant challenge is failback handling.State changes in the DR site 1106 caused by provisioning operations haveto be replicated back in the primary site 1104 after failback. In thisaspect, provisioning metadata fix-up is not a case of simple mapping(e.g., virtual machine ID) as in the above discussion of theself-contained metadata case. Provisioning operations in DR site 1106may not be replicable in the primary site 1104 after failback (due toresource limitations). One possible solution to complete handling of theresource-limit issue includes transmission of “primary site capacity”information to the DR site to control provisioning operations afterfailover.

In one or more embodiments, the following functions in the DR siterequire provisioning state tracking after disaster and prior tofailback:

-   -   1. Provision new VM    -   2. Delete VM    -   3. Modify VM (e.g., add/remove disk, add/remove CPU, add RAM,        etc.)    -   4. Network configuration changes resulting in firewall        updates—as a result of new VM provisioning or updates, do not        have to be explicitly tracked. But new security zones (VLANs)        associated with VMs have to be tracked.

Still considering preservation of VM provisioning management service andreferring now also to FIG. 12, consider actions to be taken upon DRset-up. Initially, replica VMs are set up (replicas of VMs in primarysite 1204). Element 1277 represents a replica VM (e.g., replica of VM1287) and/or a new VM created by the provisioning service 1229 in the DRsite 1206. The provisioning service in the DR site might be a differentsystem than the one used in the primary site—because the DR capabilityprovider cannot necessarily replicate provisioning tools used bydifferent customers in different primary sites, in the general case ofone or more embodiments that do not require all primary sites andmanagement services on those sites to be under the control of a single(Cloud or physical infrastructure) provider. Note the primary siteprovisioning service 1220 with its associated provisioning configurationdatabase 1283. Note also the corresponding replicas in the DR site 1206;namely, 1271 and 1230. Furthermore, note that the DR site has its ownprovisioning service 1229 and associated configuration database 1273. Asnoted, provisioning service 1229 can be the same as, or different from1230. Still considering actions to be taken upon DR set-up (i.e., beforea disaster occurs); in particular, for each primary VM to beDR-protected, replica VMs are created, their storage is allocated, thereplica VMs are quiesced, and storage replication is started at thelogical unit (LU) or volume level.

Note also primary site NW/Security Zone service 1291 and itsconfiguration database 1289, with corresponding replicas 1281, 1279.Portal 1267 provides a user interface for customer 1269 to request VMprovisioning services in the primary site. It can also be employed inthe DR site if the same provisioning service is also used in the DR siteto provision new VMs or modify and delete existing VMs after failover.As indicated by the double-ended block arrow 1263, prior to failover,storage is replicated from the primary site to the DR site; while beforefailback, storage is replicated from the DR site to the primary site.

Now considering actions to be taken upon DR set-up; replica VMs arecreated when the DR is set up using the PS 1220 used in the primary site(e.g., any suitable provisioning engine such as OpenStack, IBM Tivoli®Service Automation Manager (TSAM) (registered mark of InternationalBusiness Machines Corporation, Armonk, N.Y., USA), etc.).

Now consider actions taken by the replica site Failover Manager 1387after failover. In one or more embodiments, an initial snapshot recordswhich primary site VMs are in the DR site, and which are not. Thisinformation is in the Failover Manager 1387. This aspect in and ofitself can be carried out using known techniques. A detailed initial DRsite provisioning state of each VM is already available in the FailoverManager's local DB. This includes the number of CPUs, memory size, IPaddress(es), security zone and other resource descriptions. This isstored locally by the DR Site Failover Manager 1387. The remainingcapacity information in the primary site is extracted from the primarysite's Provisioning Service's (PS) config DB replica 1271 via PSapplication program interfaces (APIs) (even if the primary site PS isnot used in the DR site). This information can be used to restrictprovisioning operations in the DR site, to reduce (but not eliminate)the chance of provisioning adjustments failing in the primary site afterfailback. Note that the Failover Manager 1387 handles operationsrequired to transition customer workloads to the DR site after adisaster (e.g., a hurricane floods the data center) or planned failover(for data center maintenance). The Failback Manager 1297, 1299 does thereverse—it orchestrates the actions required to transition the customerworkloads back to the primary site after it has been made operationalagain (e.g., data center repaired, flood waters drained, power andcooling restored, etc.). The focus in FIGS. 11 and 12 is on what happensafter failover, up to failback to the primary site (a customer typicallycannot run the customer's business in the DR site indefinitely).

Exemplary failback preparation steps will now be described. Failbackfrom the DR site to the primary site, when the latter is operationalagain, is controlled by the Failback Manager (FM), whose function issplit into a DR site component 1299, and a primary site component 1297,both of which cooperate to orchestrate the failback operations. Onepertinent aspect in one or more embodiments is delta descriptioncomputation. The FM 1299 communicates with the DR site PS 1229 andcomputes the current provisioning state for each replica VM for site_n,and also computes the “delta description” for that VM. The FM 1299should also compute changes in the security zone, etc., as part of thedelta description. Delta description computation for Site_n is shown at1198 in FIG. 11.

Now consider exemplary actions on failback. In the case of anon-catastrophic disaster, e.g., electrical blackout or mild to moderateflood where the primary site will be operable again, after failback allprimary site VMs are restored. Non-DR-enabled VMs are restored to theirpre-disaster states that were committed to persistent storage in theprimary site (1136 for Site_n in FIG. 11). On the other hand, DR-enabledprimary VMs have to be restored to their replicated state. Thisinvolves:

-   -   1. First, performing persistent storage volume replication from        the DR site to the primary site to restore the contents of all        replicated VM disks 1275 (see 1195 in FIG. 11).    -   2. Next, VM modification operations are performed in the primary        site using the delta description (see 1196 in FIG. 11), to bring        the memory, CPU, and other resources of the primary VM(s) 1287        in synch with that of the DR site 1277 (Delta descriptions and        execution steps in the primary site FM 1297 on failback are        discussed below).

Furthermore, new VMs 1277 created in the DR site 1206 after failover arerecreated in the primary site 1204 using the delta description.Replicated VMs deleted in the DR site are also deleted in the primarysite using the delta description.

For a catastrophic disaster (primary site destroyed), after failback,there are no primary site VMs to restore, since all the persistentstorage 1136 backing up VM disks (e.g., 1285) is destroyed. Each VM inthe DR site is (newly) provisioned in the (rebuilt) primary site usingthe Initial DR site VM state+the delta description for that VM. The diskstate is then completely replicated from the DR site to the primarysite.

Consider now delta descriptions and execution steps in the primary siteFM 1297 on failback. For a catastrophic disaster, all DR site VMs arerecreated on the primary site and their disks replicated—the equivalentof DR setup in the reverse direction. For a non-catastrophic disaster,VMs newly created on the DR site are created on the primary site afterfailover. Primary VM replicas deleted in the DR site are deleted on theprimary site after failover. The table of FIG. 13 is applicable for thenon-catastrophic DR scenario, for primary VMs modified after failover.

In particular, the table of FIG. 13 shows, in the first column, variousdelta descriptions (final resource state of primary VM replica in DRsite just prior to failback less initial resource state of primary VMreplica in DR site); in the second column, corresponding provisioningoperation(s) on the primary VM during failback; and in the third column,pertinent notes (if any). When the delta description indicates thatmemory was added or removed, memory is added to or deleted from theprimary VM on failback, as the case may be. When the delta descriptionindicates that one or more CPUs were added or deleted, CPUs are added toor deleted from the primary VM on failback, as the case may be. When thedelta description indicates that one or more IP addresses were added ordeleted, IP addresses are added to or deleted from the primary VM onfailback, as the case may be.

When the delta description indicates that a disk was added or deleted, adisk is added to or removed from the primary VM on failback, as the casemay be. For each disk added in the DR site, create a new disk of thesame size in the primary VM and replicate the primary VM disk contentsfrom the DR site LU (logical unit). DR site file system changes will bereflected in the reverse replica of that volume to the primary site. Foreach disk deleted in the DR site, delete the disk in primary VM. Filesystem mount point changes are recorded in the replica of the bootvolume. When the delta description indicates that disk size wasincreased, the primary VM's disk size is increased during failback. Inone or more embodiments, this involves a workflow. For example, first,increase disk size in primary VM; second, reverse replicate disk contentfrom DR site. DR site file system changes will be reflected in reversereplica of the volume to the primary site. When the delta descriptionindicates that a security zone was added or deleted, a security zone isadded or deleted in the primary site during failback, as the case maybe. In one or more embodiments, this results in underlying firewalland/or VLAN changes.

Configuration change management database 1265 is provided in one or moreembodiments and is accessed by user 1269 via portal 1267. In one or moreembodiments, it is coupled to configuration database replica 1271.

Note also that one or more embodiments include primary site disasterrecovery manager 1292, with primary site failover manager 1294 andprimary site failback manager 1297, analogous to elements 1192, 1194,1197 in FIG. 11; as well as disaster recovery site disaster recoverymanager 1385, with disaster recovery site failover manager 1387 anddisaster recovery site failback manager 1299, analogous to elements1185, 1187, 1199 in FIG. 11.

Recapitulation Regarding Distributed Metadata

Given the discussion thus far, it will be appreciated that, in generalterms, an exemplary method, according to an aspect of the invention,includes the step of, during normal operation, at a first site 1104,1204, of a disaster recovery management unit including at least onecustomer workload machine (e.g., 1118) and at least one managementservice machine (e.g., 1120) implementing at least one managementservice, replicating to a remote disaster recovery site 1106, 1206 theat least one customer workload machine, the at least one managementservice machine, and metadata for the at least one management service.At least a portion of the metadata is not isolated within the at leastone management service. A suitable DR Manager 1192/1185 or 1292/1385e.g. can be used to set up the storage system replication when DRservice is requested by the customer, while a suitable Failover Manager1194/1187 or 1294/1387 e.g. can be used to orchestrate the transfer ofoperations (customer workloads) from the primary to the DR site duringfailover, due to a catastrophic or non-catastrophic disaster. Given theteachings herein, the skilled artisan will be able to employ known DRManagers and known Failover Managers to carry out this step. Furthersteps include, after a disaster at the first site, initiating a failoverprocess. The failover process includes bringing up, at the remotedisaster recovery site, a replicated version of the at least onecustomer workload machine (e.g., 1128); bringing up, at the remotedisaster recovery site, a replicated version of the at least onemanagement service machine (e.g., 1130); operating, at the remotedisaster recovery site, the replicated version of the at least onecustomer workload machine and the replicated version of the at least onemanagement service machine, in accordance with the metadata for the atleast one management service; and creating an initial snapshot of adistributed metadata state of the metadata for the at least onemanagement service implemented on the replicated version of the at leastone management service machine. The process of bringing up the replicasand operating the DR site can be orchestrated by the Failover Manager.The initial snapshot can be created by the Failover Manager and/or theFailback Manager.

Furthermore in this regard, in one or more embodiments, right after thedisaster, the Failover Manager and/or the Failback Manager takes acheckpoint (i.e., creates an initial state description of every managedservice with distributed metadata to determine what the state is rightafter the disaster). This is useful since, before failback, the deltadescription is to be calculated and the delta description is thedifference between the state just before failback and the state justafter failover. Accordingly, a snapshot is taken of the distributedmetadata state of every managed service with distributed metadata sothat the delta description can be computed during failback.

Furthermore, subsequent to initiating the failover process, a failbackprocess is initiated. The failback process includes creating arepresentation of state changes for the at least one management serviceimplemented on the replicated version of the at least one managementservice machine made in the remote disaster recovery site since thefailover process and calculating therefrom a delta description from theinitial snapshot. See 1198 in FIG. 11, e.g. In at least someembodiments, this step is carried out by the replica site failbackmanager interacting with the replica managed service and relatedcomponents. The failback process further includes transmitting the deltadescription of the managed service state changes to the first site (forexample, the replica site failback manager transmits the deltadescription of the managed service state changes to the first sitefailback manager (see 1196 in FIG. 11, e.g.)). The failback processstill further includes creating a reverse replica (e.g., host based orstorage system based) of all the workload components from the remotedisaster recovery site at the first site and playing back the deltadescription to restore a distributed metadata state that existed in theremote disaster recovery site and re-create it in the first site. Forexample, the primary site failback manager may create the reversereplica and play back the delta description received from the replicasite failback manager to restore the distributed metadata state.

In one or more embodiments, the Failback Manager 1197-1 or 1197-2 and1199 orchestrates the transfer of operations from the DR site to theprimary site when it is restored, either to its pre-disaster state for anon-catastrophic disaster, or to a “bare metal” state after acatastrophic disaster. Special logic is employed in the Failback Managerwhen management services are protected by DR and are failed back, andthe management services have distributed metadata, not limited to beingstored in the Management Service node(s) only.

It will be appreciated that, in general, the disaster recoverymanagement unit can be located within a cloud environment or a non-cloudenvironment. Furthermore, the at least one customer workload machine andthe at least one management service machine can be non-virtualizedphysical machines or virtual machines executing on one or more physicalmachines under control of a hypervisor. Indeed, one or more embodimentscan be applied to physical machines, where the provision servicecreates, modifies, and deletes physical machines instead of virtualmachines. One or more embodiments apply in that case as well, since themachines in the replica (DR) site may not be identical to those in theprimary site, and also the resource pool in the two sites may not beidentical. However, some operations such as add/delete CPU are notautomated provisioning operations on physical machines, so some of thedescriptions of provisioning operations and associated delta descriptionare not applicable to a non-virtualized scenario.

Furthermore, it should again be pointed out that one or more embodimentsare generally applicable to preserving management services withdistributed metadata through the disaster recovery life cycle, and arenot limited to provisioning; provisioning scenarios are set forth hereinas non-limiting exemplary embodiments.

In some instances, the at least one management service includes aprovisioning service, and a further step includes, subsequent to thestep of operating the replicated version of the at least one customerworkload machine and the replicated version of the at least onemanagement service machine in accordance with the metadata for the atleast one management service, carrying out and tracking additionalprovisioning at the remote disaster recovery site (e.g., with 1129,1229). Note that one or more embodiments track the additionalprovisioning not by tracking each provisioning operation, but rather byonly tracking the differences, as discussed below. An even further stepincludes, subsequent to the additional provisioning, upon the first sitecoming back up, restoring the first site to reflect the trackedadditional provisioning (e.g., via cooperation between 1199 and 1197-2).Such additional provisioning can include, by way of example and notlimitation, provisioning a new virtual machine, deleting an existingvirtual machine, modifying an existing virtual machine, and/orestablishing at least one new security zone associated with an existingvirtual machine.

In some instances, the replicating to the remote disaster recovery siteincludes host-based replication; the provisioning service includes aprimary site provisioning service 1120 used at the first site 1104; andthe carrying out and tracking of the additional provisioning at theremote disaster recovery site is carried out with a remote disasterrecovery site provisioning service 1129 different than the primary siteprovisioning service. The skilled artisan will appreciate thathost-based replication is a form of replication where software runningon each server/machine (virtual or physical) controls replications ofthe disks of that server alone to a remote replica site. Host-basedreplication per se is known to the skilled artisan, who, given theteachings herein, will be able to adapt one or more known host-basedreplication techniques to implement one or more embodiments.

On the other hand, in some cases, the replicating to the remote disasterrecovery site includes storage-based replication; the provisioningservice includes a primary site provisioning service 1120 used at thefirst site 1104; and the carrying out and tracking of the additionalprovisioning at the remote disaster recovery site is carried out withthe replicated version 1130 of the at least one management servicemachine (1129=1130). It will be appreciated that the choice ofreplication technology—host-based or storage-based, is orthogonal to thecondition of whether the provisioning service in the replica site is thesame as or different from the provisioning service in the primary site.

Referring again to FIG. 12, in some cases, a further step includes,subsequent to the additional provisioning and prior to restoring thefirst site 1204 to reflect the tracked additional provisioning,calculating for each virtual machine 1277 in the remote disasterrecovery site a delta description including a pre-failback state of agiven one of the virtual machines less an initial state of the given oneof the virtual machines on failover. The delta description in essencecaptures the differences in the state for each VM between thepost-failover state and the pre-failback state. It is different from alog of all state changes that are made to a VM. E.g., a VM with apost-failover state=2 GB of RAM, whose memory size is increased 3 timesby 2 GB, represents a single entry in the delta description: memoryincrease by 6 GB.

In some such cases, the disaster is a catastrophic disaster, and therestoring of the first site to reflect the tracked additionalprovisioning includes newly provisioning each of the virtual machines1277 in the remote disaster recovery site into the first site inaccordance with an initial remote disaster recovery site virtual machinestate for each of the virtual machines in the remote disaster recoverysite modified by a corresponding one of the delta descriptions. This isfollowed by replication of the contents of each disk of that VM from thereplica site to the primary site.

On the other hand, in some such cases, the disaster is anon-catastrophic disaster, and the restoring of the first site toreflect the tracked additional provisioning includes a number ofsub-steps, as appropriate. Non-replicated virtual machines from thefirst site (i.e., VMs in primary site that were not replicated to the DRsite) are restored to a pre-disaster state from persistent storage(e.g., 1136) in the first site. (Note as an aside that element 1285 is avirtual disk of a virtual machine; physical storage backing up suchvirtual disks is the storage system in the primary site, e.g., 1136.)Consider those of the virtual machines 1277 in the remote disasterrecovery site that are undeleted replicated virtual machines (i.e., VMsfrom the primary site that were replicated to the DR site and were notsubsequently deleted). These are replicated back into the first site bycarrying out persistent storage volume replication from the remotedisaster recovery site to the first site and modifying the restoredvirtual machines at the first site in accordance with corresponding onesof the delta descriptions. Consider also those of the virtual machines1277 in the remote disaster recovery site that are newly-created virtualmachines (i.e., VMs newly created in the DR site after failover). Theseare replicated into the first site by recreating them in the first sitein accordance with corresponding ones of the delta descriptions.Finally, consider those of the virtual machines in the remote disasterrecovery site that are deleted replicated virtual machines (i.e., VMsfrom the primary site that were replicated to the DR site and weresubsequently deleted). The corresponding VMs in the first site aresimply deleted.

One or more embodiments of the invention, or elements thereof, can beimplemented in the form of an apparatus including a memory and at leastone processor that is coupled to the memory and operative to performexemplary method steps.

One or more embodiments can make use of software running on a generalpurpose computer or workstation. With reference to FIG. 1, such animplementation might employ, for example, a processor 16, a memory 28,and an input/output interface 22 to a display 24 and external device(s)14 such as a keyboard, a pointing device, or the like. The term“processor” as used herein is intended to include any processing device,such as, for example, one that includes a CPU (central processing unit)and/or other forms of processing circuitry. Further, the term“processor” may refer to more than one individual processor. The term“memory” is intended to include memory associated with a processor orCPU, such as, for example, RAM (random access memory) 30, ROM (read onlymemory), a fixed memory device (for example, hard drive 34), a removablememory device (for example, diskette), a flash memory and the like. Inaddition, the phrase “input/output interface” as used herein, isintended to contemplate an interface to, for example, one or moremechanisms for inputting data to the processing unit (for example,mouse), and one or more mechanisms for providing results associated withthe processing unit (for example, printer). The processor 16, memory 28,and input/output interface 22 can be interconnected, for example, viabus 18 as part of a data processing unit 12. Suitable interconnections,for example via bus 18, can also be provided to a network interface 20,such as a network card, which can be provided to interface with acomputer network, and to a media interface, such as a diskette or CD-ROMdrive, which can be provided to interface with suitable media.

Accordingly, computer software including instructions or code forperforming the methodologies of the invention, as described herein, maybe stored in one or more of the associated memory devices (for example,ROM, fixed or removable memory) and, when ready to be utilized, loadedin part or in whole (for example, into RAM) and implemented by a CPU.Such software could include, but is not limited to, firmware, residentsoftware, microcode, and the like.

A data processing system suitable for storing and/or executing programcode will include at least one processor 16 coupled directly orindirectly to memory elements 28 through a system bus 18. The memoryelements can include local memory employed during actual implementationof the program code, bulk storage, and cache memories 32 which providetemporary storage of at least some program code in order to reduce thenumber of times code must be retrieved from bulk storage duringimplementation.

Input/output or I/O devices (including but not limited to keyboards,displays, pointing devices, and the like) can be coupled to the systemeither directly or through intervening I/O controllers.

Network adapters 20 may also be coupled to the system to enable the dataprocessing system to become coupled to other data processing systems orremote printers or storage devices through intervening private or publicnetworks. Modems, cable modem and Ethernet cards are just a few of thecurrently available types of network adapters.

As used herein, including the claims, a “server” includes a physicaldata processing system (for example, system 12 as shown in FIG. 1)running a server program. It will be understood that such a physicalserver may or may not include a display and keyboard.

One or more embodiments are particularly significant in the context of acloud or virtual machine environment, although this is exemplary andnon-limiting. Reference is made back to FIGS. 1-3 and accompanying text.

It should be noted that any of the methods described herein can includean additional step of providing a system comprising distinct softwaremodules embodied on a computer readable storage medium; the modules caninclude, for example, any or all of the appropriate elements depicted inthe block diagrams and/or described herein; by way of example and notlimitation, any one, some or all of the modules/blocks and orsub-modules/sub-blocks in the figures; e.g., disaster recovery managerwith components at primary site and disaster recovery site; failovermanager with components at primary site and disaster recovery site;failback manager with components at primary site and disaster recoverysite. The method steps can then be carried out using the distinctsoftware modules and/or sub-modules of the system, as described above,executing on one or more hardware processors such as 16. Further, acomputer program product can include a computer-readable storage mediumwith code adapted to be implemented to carry out one or more methodsteps described herein, including the provision of the system with thedistinct software modules.

Exemplary System and Article of Manufacture Details

The present invention may be a system, a method, and/or a computerprogram product. The computer program product may include a computerreadable storage medium (or media) having computer readable programinstructions thereon for causing a processor to carry out aspects of thepresent invention.

The computer readable storage medium can be a tangible device that canretain and store instructions for use by an instruction executiondevice. The computer readable storage medium may be, for example, but isnot limited to, an electronic storage device, a magnetic storage device,an optical storage device, an electromagnetic storage device, asemiconductor storage device, or any suitable combination of theforegoing. A non-exhaustive list of more specific examples of thecomputer readable storage medium includes the following: a portablecomputer diskette, a hard disk, a random access memory (RAM), aread-only memory (ROM), an erasable programmable read-only memory (EPROMor Flash memory), a static random access memory (SRAM), a portablecompact disc read-only memory (CD-ROM), a digital versatile disk (DVD),a memory stick, a floppy disk, a mechanically encoded device such aspunch-cards or raised structures in a groove having instructionsrecorded thereon, and any suitable combination of the foregoing. Acomputer readable storage medium, as used herein, is not to be construedas being transitory signals per se, such as radio waves or other freelypropagating electromagnetic waves, electromagnetic waves propagatingthrough a waveguide or other transmission media (e.g., light pulsespassing through a fiber-optic cable), or electrical signals transmittedthrough a wire.

Computer readable program instructions described herein can bedownloaded to respective computing/processing devices from a computerreadable storage medium or to an external computer or external storagedevice via a network, for example, the Internet, a local area network, awide area network and/or a wireless network. The network may comprisecopper transmission cables, optical transmission fibers, wirelesstransmission, routers, firewalls, switches, gateway computers and/oredge servers. A network adapter card or network interface in eachcomputing/processing device receives computer readable programinstructions from the network and forwards the computer readable programinstructions for storage in a computer readable storage medium withinthe respective computing/processing device.

Computer readable program instructions for carrying out operations ofthe present invention may be assembler instructions,instruction-set-architecture (ISA) instructions, machine instructions,machine dependent instructions, microcode, firmware instructions,state-setting data, or either source code or object code written in anycombination of one or more programming languages, including an objectoriented programming language such as Smalltalk, C++ or the like, andconventional procedural programming languages, such as the “C”programming language or similar programming languages. The computerreadable program instructions may execute entirely on the user'scomputer, partly on the user's computer, as a stand-alone softwarepackage, partly on the user's computer and partly on a remote computeror entirely on the remote computer or server. In the latter scenario,the remote computer may be connected to the user's computer through anytype of network, including a local area network (LAN) or a wide areanetwork (WAN), or the connection may be made to an external computer(for example, through the Internet using an Internet Service Provider).In some embodiments, electronic circuitry including, for example,programmable logic circuitry, field-programmable gate arrays (FPGA), orprogrammable logic arrays (PLA) may execute the computer readableprogram instructions by utilizing state information of the computerreadable program instructions to personalize the electronic circuitry,in order to perform aspects of the present invention.

Aspects of the present invention are described herein with reference toflowchart illustrations and/or block diagrams of methods, apparatus(systems), and computer program products according to embodiments of theinvention. It will be understood that each block of the flowchartillustrations and/or block diagrams, and combinations of blocks in theflowchart illustrations and/or block diagrams, can be implemented bycomputer readable program instructions.

These computer readable program instructions may be provided to aprocessor of a general purpose computer, special purpose computer, orother programmable data processing apparatus to produce a machine, suchthat the instructions, which execute via the processor of the computeror other programmable data processing apparatus, create means forimplementing the functions/acts specified in the flowchart and/or blockdiagram block or blocks. These computer readable program instructionsmay also be stored in a computer readable storage medium that can directa computer, a programmable data processing apparatus, and/or otherdevices to function in a particular manner, such that the computerreadable storage medium having instructions stored therein comprises anarticle of manufacture including instructions which implement aspects ofthe function/act specified in the flowchart and/or block diagram blockor blocks.

The computer readable program instructions may also be loaded onto acomputer, other programmable data processing apparatus, or other deviceto cause a series of operational steps to be performed on the computer,other programmable apparatus or other device to produce a computerimplemented process, such that the instructions which execute on thecomputer, other programmable apparatus, or other device implement thefunctions/acts specified in the flowchart and/or block diagram block orblocks.

The flowchart and block diagrams in the Figures illustrate thearchitecture, functionality, and operation of possible implementationsof systems, methods, and computer program products according to variousembodiments of the present invention. In this regard, each block in theflowchart or block diagrams may represent a module, segment, or portionof instructions, which comprises one or more executable instructions forimplementing the specified logical function(s). In some alternativeimplementations, the functions noted in the block may occur out of theorder noted in the figures. For example, two blocks shown in successionmay, in fact, be executed substantially concurrently, or the blocks maysometimes be executed in the reverse order, depending upon thefunctionality involved. It will also be noted that each block of theblock diagrams and/or flowchart illustration, and combinations of blocksin the block diagrams and/or flowchart illustration, can be implementedby special purpose hardware-based systems that perform the specifiedfunctions or acts or carry out combinations of special purpose hardwareand computer instructions.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the invention. Asused herein, the singular forms “a”, “an” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprises”and/or “comprising,” when used in this specification, specify thepresence of stated features, integers, steps, operations, elements,and/or components, but do not preclude the presence or addition of oneor more other features, integers, steps, operations, elements,components, and/or groups thereof.

The corresponding structures, materials, acts, and equivalents of allmeans or step plus function elements in the claims below are intended toinclude any structure, material, or act for performing the function incombination with other claimed elements as specifically claimed. Thedescription of the present invention has been presented for purposes ofillustration and description, but is not intended to be exhaustive orlimited to the invention in the form disclosed. Many modifications andvariations will be apparent to those of ordinary skill in the artwithout departing from the scope and spirit of the invention. Theembodiment was chosen and described in order to best explain theprinciples of the invention and the practical application, and to enableothers of ordinary skill in the art to understand the invention forvarious embodiments with various modifications as are suited to theparticular use contemplated.

1.-12. (canceled)
 13. A non-transitory computer readable mediumcomprising computer executable instructions which when executed by acomputer cause the computer to perform the method of: during normaloperation, at a first site, of a disaster recovery management unitcomprising at least one customer workload machine and at least onemanagement service machine implementing at least one management service,replicating to a remote disaster recovery site said at least onecustomer workload machine, said at least one management service machine,and metadata for said at least one management service, at least aportion of said metadata not being isolated within said at least onemanagement service; after a disaster at said first site, initiating afailover process comprising: bringing up, at said remote disasterrecovery site, a replicated version of said at least one customerworkload machine; bringing up, at said remote disaster recovery site, areplicated version of said at least one management service machine;operating, at said remote disaster recovery site, said replicatedversion of said at least one customer workload machine and saidreplicated version of said at least one management service machine, inaccordance with said metadata for said at least one management service;and creating an initial snapshot of a distributed metadata state of saidmetadata for said at least one management service implemented on saidreplicated version of said at least one management service machine;subsequent to initiating said failover process, initiating a failbackprocess comprising: creating a representation of state changes for saidat least one management service implemented on said replicated versionof said at least one management service machine made in said remotedisaster recovery site since said failover process and calculatingtherefrom a delta description from said initial snapshot; transmittingsaid delta description to said first site; and creating a reversereplica of all the workload components from the remote disaster recoverysite at the first site and playing back the delta description to restorea distributed metadata state that existed in the remote disasterrecovery site and re-create it in the first site.
 14. The non-transitorycomputer readable medium of claim 13, wherein said at least onemanagement service comprises a provisioning service, further comprisingcomputer executable instructions which when executed by the computercause the computer to perform the additional method steps of: subsequentto said step of operating said replicated version of said at least onecustomer workload machine and said replicated version of said at leastone management service machine in accordance with said metadata for saidat least one management service, carrying out and tracking additionalprovisioning at said remote disaster recovery site; and subsequent tosaid additional provisioning, upon said first site coming back up,restoring said first site to reflect said tracked additionalprovisioning.
 15. The non-transitory computer readable medium of claim14, wherein said additional provisioning comprises provisioning a newvirtual machine.
 16. The non-transitory computer readable medium ofclaim 14, wherein said additional provisioning comprises deleting anexisting virtual machine.
 17. An apparatus comprising: a memory; and atleast one processor, coupled to said memory, and operative to: duringnormal operation, at a first site, of a disaster recovery managementunit comprising at least one customer workload machine and at least onemanagement service machine implementing at least one management service,replicate to a remote disaster recovery site said at least one customerworkload machine, said at least one management service machine, andmetadata for said at least one management service, at least a portion ofsaid metadata not being isolated within said at least one managementservice; after a disaster at said first site, initiate a failoverprocess comprising: bringing up, at said remote disaster recovery site,a replicated version of said at least one customer workload machine;bringing up, at said remote disaster recovery site, a replicated versionof said at least one management service machine; operating, at saidremote disaster recovery site, said replicated version of said at leastone customer workload machine and said replicated version of said atleast one management service machine, in accordance with said metadatafor said at least one management service; and creating an initialsnapshot of a distributed metadata state of said metadata for said atleast one management service implemented on said replicated version ofsaid at least one management service machine; subsequent to initiatingsaid failover process, initiate a failback process comprising: creatinga representation of state changes for said at least one managementservice implemented on said replicated version of said at least onemanagement service machine made in said remote disaster recovery sitesince said failover process and calculating therefrom a deltadescription from said initial snapshot; transmitting said deltadescription to said first site; and creating a reverse replica of allthe workload components from the remote disaster recovery site at thefirst site and playing back the delta description to restore adistributed metadata state that existed in the remote disaster recoverysite and re-create it in the first site.
 18. The apparatus of claim 17,wherein said at least one management service comprises a provisioningservice, and wherein said at least one processor is further operativeto: subsequent to operating said replicated version of said at least onecustomer workload machine and said replicated version of said at leastone management service machine in accordance with said metadata for saidat least one management service, carry out and tracking additionalprovisioning at said remote disaster recovery site; and subsequent tosaid additional provisioning, upon said first site coming back up,restore said first site to reflect said tracked additional provisioning.19. The apparatus of claim 18, wherein said additional provisioningcomprises provisioning a new virtual machine.
 20. The apparatus of claim18, wherein said additional provisioning comprises deleting an existingvirtual machine.